1. Field of the Invention
The present invention relates to hold open rods generally and, more particularly, but not by way of limitation, to a novel hold open rod that employs rotatably mounted pawls as locking members and a snubber.
2. Background Art
The following patents are known:
U.S. Pat. No. 3,367,689, issued Feb. 6, 1968, to McCarthy, and titled ADJUSTABLE STRUT, discloses a lengthwise adjustable strut that uses a dumbbell-shaped, loose member as a locking member.
U.S. Pat. No. 3,390,874, issued Jul. 2, 1968, to McCarthy, and titled TELESCOPIC STRUT, discloses a lengthwise adjustable strut that uses a cylindrical, loose member as a locking member.
U.S. Pat. No. 3,442,541, issued May 6, 1969, to Metz, and titled RELEASABLE FASTENER, discloses a lengthwise adjustable strut that uses a toothed, radially movable, loose member as a locking member.
U.S. Pat. No. 3,469,871, issued Sep. 30, 1969, to Betts, and titled RELEASABLE LOCKING DEVICE, discloses a lengthwise adjustable strut that uses one or more loose members as locking members.
U.S. Pat. No. 3,945,744, issued Mar. 23, 1976, to Metz and titled TELESCOPING STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose dogs as locking members.
U.S. Pat. No. 4,014,467, issued Mar. 29, 1977, to Ferguson, and titled DISHWASHER AND COUPLING, discloses a lengthwise adjustable coupling that uses one or more loose balls as coupling members.
U.S. Pat. No. 4,362,415, issued Dec. 7, 1982, to Metz et al., and titled EXTENSIBLE AND RETRACTABLE STRUT WITH SAFETY LATCH, discloses a lengthwise adjustable strut that uses a spring-loaded lever as a locking member.
U.S. Pat. No. 4,366,945, issued Jan. 4, 1983, to Blaüenstein, and titled HOSE COUPLING WITH DOUBLE LOCK, discloses a hose coupling that uses one or more loose balls as locking elements.
U.S. Pat. No. 4,453,449, issued Jun. 12, 1984, to Hollmann, and titled HOLDING APPARATUS, discloses a lengthwise adjustable holding apparatus that uses one or more loose balls as locking members.
U.S. Pat. No. 4,453,748, issued Jun. 12, 1984, to Ekman, and titled QUICK-COUPLING MEMBER, discloses a quick-coupling that uses one or more loose balls as locking members.
U.S. Pat. No. 4,546,956, issued Oct. 15, 1985, to Moberg, and titled COMPRESSED AIR COUPLING, discloses a compressed air coupling that uses one or more loose balls as locking members.
U.S. Pat. No. 4,682,795, issued Jul. 28, 1987, to Rabushka et al., and titled TENSION ACTUATED UNCOUPLER, discloses an uncoupler that uses one or more loose balls as locking members.
U.S. Pat. No. 4,960,344, issued Oct. 2, 1990, to Geisthoff et al., and titled LOCKING MECHANISM FOR FIXING AN OUTER PART ON AN INNER PART, discloses a lengthwise adjustable part that uses one or more loose balls as locking members.
U.S. Pat. No. 5,066,049, issued Nov. 19, 1991, to Staples, and titled LOCKOUT DEVICE FOR HOSE FITTING, discloses a hose fitting that uses one or more loose balls as locking members.
U.S. Pat. No. 5,265,970, issued Nov. 30, 1993, to LaBarre, and titled STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose balls as locking members.
U.S. Pat. No. 5,366,313, issued Nov. 22, 1994, to LaBarre, and titled STRUT CONSTRUCTION, discloses a lengthwise adjustable strut that uses one or more loose balls as locking members.
U.S. Pat. No. 5,579,875, issued Dec. 3, 1996, to Vargas et al., and titled SELF LOCKING STRUT, describes a lengthwise adjustable strut that uses spring-loaded pins as locking members.
U.S. Pat. No. 5,632,568, issued May 27, 1997, to Fechter, and titled AUTOMATIC UNCOCKING SHAFT SENSING COUPLER, discloses an uncocking shaft sensing coupler that uses one or more loose dogs or balls as locking members.
U.S. Pat. No. 5,779,385, issued Jul. 14, 1998, to Fechter, and titled AUTOMATIC UNCOCKING SHAFT SENSING COUPLER, discloses an uncocking shaft sensing coupler that uses one or more loose dogs or balls as locking members.
U.S. Pat. No. 5,950,997, issued Sep. 14, 1999, to Metz, and titled TELESCOPING STRUT CONSTRUCTION, discloses a lengthwise adjustable three-member strut that uses one or more loose locking dogs and a spring-loaded member as locking members.
In connection with most prior hold open rods or struts, there have existed significant problems involving inadvertent release under load. Specifically, with either compressive or tensile loads applied between the telescoping members of the prior art hold open rods or struts, there was a danger that the operator could accidentally slide the locking collar to a release position while the hold open rod or strut was still under load, possibly leading to a sudden collapse of the hold open rod or strut and an accompanying uncontrollable swing or fall of the component being held by virtue of its own weight. Such a condition was capable of causing serious injury or death to either the operator or other personnel in the area.
In the past, hold open rods or struts of the type noted have been used with aircraft cowlings, in order to retain the cowlings in an open position as during maintenance, and/or servicing of the aircraft engine. Depending on the size of the aircraft, such cowlings can weigh hundreds of pounds, and the potential of injury resulting from being struck by an inadvertently released cowling can be readily appreciated if one considers structures of such magnitude and size.
The more recently issued patents address this problem and require that a compressive load be removed, mechanically or manually, from the hold open rod or strut before the release collar can be moved and the hold open rod or strut thereafter collapsed. None of the cited patents require that the release mechanism be rotated a significant degree before the hold open rod can be collapsed. Such devices also still employ loose balls or dogs as the locking members and fail to address the following problems:                In an intermediate position, the prior art hold open rods or struts do not offer locking under tensile loads.        Because the dogs are loosely retained, instances occur when the dogs actually roll over within their slots, causing jamming and non-lockup conditions. These instances can occur particularly under extreme vibration situations.        Due to a point contact of the dogs to the inner tube, there is less holding capacity than if a line contact were provided.        Because of the loose balls and dogs, there is more wear on the inner tube and release collar under vibration.        Because the loose balls and dogs can fall out, the devices offer less than failsafe designs.        
None of the forgoing patents discloses the use of one or more rotatably mounted pawls as locking members.
Accordingly, it is a principal object of the present invention to provide a hold open rod that offers locking in the intermediate position under tensile loads.
It is a further object of the invention to provide such a hold open rod that prevents the locking members from rolling over within their slots.
It is an additional object of the invention to provide such a hold open rod that provides a line contact between the locking members thereof and the surface on which they ride, thus offering more holding capacity.
It is another object of the invention to provide such a hold open rod that provides locking members that are not loose.
A further object of the invention is to provide such a hold open rod in which the locking members thereof cannot fall out, thus providing a more failsafe design.
An additional object of the invention is to provide such a hold open rod with a vibration snubber as part of thereof.
Another object of the invention is to provide such a hold open rod that cannot be collapsed before rotating the release mechanism thereof a significant degree.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.